In order to properly answer this question, I must start by making one point very clear: no single race is more or less intelligent than any other. Arguments about inventions and technological advancements fall short of fully capturing the complexities of human development and geography. For a more comprehensive look at that subject, I’d suggest reading Jared Diamond’s incredible book, Guns, Germs and Steel.
Korean, Singaporean and Japanese grade school students routinely top the list in science and mathematics, but the scores in The Netherlands, Belgium and Finland are consistently high as well and often rival their Asian counterparts. Thus, making a statement that Asians are smart(er) is not only stereotypical, but it’s not statistically accurate. Still, there are some cultural elements in parts of Asia that create an environment more conducive to academic success that might not be found in other parts of the world.
Historically, and particularly in East Asia, society was bitterly stratified making any sort of mobility tremendously difficult as your fate was often determined by the status of the family you were born into. There was, however, an option for upward movement through the passage of a civil service examination. Once passed, one could join the literati or intellectual class thus cementing their family's elevated status for generations to come. While some form of this test still exists in many nations, the effect it has had on the psyche of the populace greatly outweighs the specific exam itself.